Conventionally, display driver circuits for driving display portions such as liquid crystal display devices are mounted on, for example, glass substrates in the form of, for example, chips, and they receive video signals externally provided via flexible printed circuit (hereinafter, referred to as “FPC”) boards connected to the glass substrates, and display video on the display portions.
The interface specifications used in methods for transmitting the video signals externally provided via the FPC boards are roughly divided into two types, i.e., serial and parallel modes. Usually, either of these is employed but both of them may be used together. For example, some discrete devices, such as cell phones and hand-held computers, include two or more display portions and a corresponding number of display driver circuits.
In such a configuration, typically, video signals are transmitted in the parallel mode to a circuit for driving a display portion closer to a main board that generated the video signals, and in the serial mode to a circuit for driving a display portion farther from the main board. It is conceivable that in such a device, different display driver circuits, each corresponding to only one of the interface specifications, are used for each of the circuits for driving the display portions, but this results in an increased number of parts and hence increased device production cost.
Therefore, by using display driver circuits each being provided with input terminals compatible with the two types of interface specifications, it is rendered possible to use driver circuits of the same configuration (i.e., of the same type) for any display portions, which results in reduced production cost.
Furthermore, for two display devices using two different interface specifications, by using such display driver circuits each being provided with input terminals compatible with the two types of interface specifications, it is rendered possible to commonly use driver circuits of the same configuration for both of the display devices, which results in reduced production cost as well.
Note that Japanese Laid-Open Utility Model Publication No. 1-79137 discloses a configuration of a graphic display device compatible with both the parallel and the serial interface specification.